Compression of digital image content is performed to reduce the content size to facilitate more efficient transmission and storage of the image. Existing compression techniques for images or image sequences use algorithms that analyze the image frame or frame sequences as a whole without consideration to the contents of the image. The technique may then apply a lossy compression to discard as much data as possible without significantly compromising image quality. This can lead to overcompressing important content and/or undercompressing unimportant content.
For example, in video compression the encoder may be given leeway to choose what areas of an image to update with what fidelity. Moreover, there is flexibility in how sequential frames are represented, in that for a particular frame there can be delivered data that essentially constitutes a resolvable photograph, or the frame can be defined based on previous and/or future frames in the sequence. Regardless, a single level of compression is typically applied. Such image compression decisions are usually made based on a whole-image quality metric. For example, the goal can be to avoid occurrence of excessive artifacts in the center of the image, or at the edges. That is, the same level of compression is applied throughout the image.